Implant and follow-up data
For all included leads, sensing, and pacing threshold, and impedance
were recorded at discharge time and their regular follow-up. Sensing and
pacing thresholds were calculated for a pulse duration of 0.4
milliseconds. At follow-up time, failure of a lead and its reason also
were recorded. The reason for failure was either primary or secondary.
Primary reasons for failure included replacement due to unacceptable
high pacing threshold and sensing abnormality, lead fracture, loss of
capture, and lead displacement. Secondary ones consisted of infection of
the generator pocket and accidentally lead damage during heart surgery.
The lead survival time (duration of being functional) was calculated as
the interval between lead implantation and the time that failure was
observed in the clinical follow-up. When a failure occurred, and a lead
was exchanged, the new lead enrolled in the study and the patient
characteristics (demographics, electrocardiographic and
echocardiographic features) at the time of lead implantation were
enrolled.